The present invention is directed to an inking ribbon for color transfer under the influence of heat, which ribbon comprises a carrier layer supporting a heat-soluble release layer which holds a colored layer to the carrier layer.
U.S. Pat. No. 4,453,839, whose disclosure is incorporated by reference thereto and which was the basis of European published application No. 0 096 740, discloses an inking ribbon which has a carrier layer which is composed of a solid polymer containing the inclusion of electrically conductive carbon black, and this carrier layer is additionally coated with a thin aluminum layer. A release layer composed of an alcane or crystalline polyethylene having a melting temperature of around 108.degree. C. is applied to the carrier layer or, respectively, to the aluminum layer. A colored layer containing a coloring agent and bonding agent adheres to this release layer. For the printing of a picture element, electrical current is introduced into the electrically conductive carrier layer via electrodes of a thermal printing head. The current flux leads to a local heating of the carrier layer so that the release layer lying therebelow melts to release the underlying portion of the colored layer, which portion is transferred onto a recording medium, which is usually paper and which is brought into contact with the inking ribbon. The inking ribbon must be separated from the recording medium immediately after color transfer in order to separate the applied portion of color from the melted release layer before this release layer solidifies again and the release portion of color can then adhere to it again. To this end, the inking ribbon is drawn away from the recording medium following the printing zone and is drawn away therefrom at a large angle. Thus, a step-by-step feed of the recording medium is, therefore, not possible, and this step-by-step feed is usually required particularly when using thermal printing heads, which comprise printing elements that are arranged in series and are driven successively by groups.